Carburetor



Dec. 13, 1927. 1,652,859 I v. 11.. HEETLER? Hill Patented Dec. 13, 1 927. I

- UNITED I STATES 1,653,859 PATENT v OFFICE.

VICTOR R. HEFTLER, OF DETROIT, MICHIGAN, .ASSIGNOR TO SOCIETE DU GARBURATE'U'R ZENITH, OF LYON, FRANCE, A CORPO RATION OF FRANCE.

- cARBU EToR.

Application filed April 7,

The present inventionrelates /bro adly to carburetors, and more particularly to a fuel f feed for carburetors of the type adapted to be utilized with internal combustion engines. It has heretofore been proposed to provide fuel feeding jets having a vent opening to the atmosphere. It has also been proposed T to provide single jets each having a series of :openingseflective as vents and adapted to be successively uncovered 1n accordance with the increasing demands upon the carburetor.

- Such constructions, while partially satisfactory for certain purposes and at certain speeds, have usually produced a so-called bad spot requiring some form of corrective device.

This invention relates particularly to a fuel feeding system comprising a plurality of jets some or all of which. are vented to provide means for admitting air thereto anterior to the point of discharge, and in.

e which such jets as are vented'have but a single air 0 ening leading thereto. ,In this 'manner,.t e objections inherent in a conments of my invention, and that changes may be made in the'construction and operathe spiritof the invention or the scope of tion disclosedherein without departing from my claim.

In the drawings,' Figure 1 is a'diagrammatic view illustrating one enibodiment of the present invention;

Figure 2 is a view similar to Figure 1 illustrating another embodiment of my invention 1 Figure 3 is a.. vertical sectional view through a carburetor of commercial form constructed in accordance with the disclosure Figures 4, 5, and-6 .are illustrative of different'typesof jets which maybe utilized in; accordance with my invention; 1 g

7 .is a perspective vlew, partly in section," illustrating one form of fuel feeding IXIX of Figure 7.

'ferred to and also tojthe amounts of 1922. Serial No. 550,360.

device, the jets being in assembled relation; Figure 8 is a detail sectional view on theline VII IVIII of Figure 7; and

Figure 9 is a detail sectional view on line By a series of experiments I have found that the bad spots hereinbefore referred to are caused in an air vented jet carburetor by the irregular introduction of air within the jet.- In the given condition of'suction t which this bad spot occurs, the'bubbles' of a1r eral y comparable to the time interval between successive explosions. These spurts of fuel form rich shots, while the bubbles of air form lean shots. These successive shots where the time interval is comparable to that between explosions," go to different cylinders. This necessarily means a poor combustion mixture in all of the cylinders, thereby causing the so-called bad spots. .This,condiget into the fuel at intervals of time gention is more noticeable at one speed than another, due partly to the time intervals rea1r present in the emulsion.

With the present invention, I e'ifectively overcome the objectionable effects of such bad spots. The results accomplishedmay be attributed-either to the formation, with the present invention, of a bad spot having a 8 less effect at any one time, by making the emulsion constitute a less'proportion of the total fuel being fed, or by the intermittent formation of such an emulsion and the distributing or attenuating of the resulting bad spots over a longer total range, the emulsion formed at any one time bytransition from one critical speed to another extendingthrough a small range of" suction, which range cannot be maintained. Either or both of these operations have the desired effect, producing a fuel feed in which the bad spot is not fel Before going into a detail description of the present inventiomit may be stated that with a simple suctionjetain a fixed air passage, the feed of fuel is a function of the suction, the flow increasing as the suction increases. The law of flow through a single air vented jet, that is, a jet having a single.

orifice for admitting air thereto anterior to its point of delivery into the main air stream too is discontinuous, and a change in the character of the flow occurs when thesuction at the outlet has reached a value high enough to cause the level of the fuel in the atmospheric well to uncover the air bleeding orifice. This value of the suction I have called a critical suction. The critical suction depends on the vertical distance between the point where the fuel is delivered into the carbureting passage or chamber and the point where air is admitted in o e 1 0 stream and on the relative size of the feed hole into the well and 'ofthe restriction 'controlling the outlet from the well. It will he plain that if the feed hole to the well is very large, the level of the. fuel in the well will drop less for a given suction at. the delivery outlet than if the feed .hole is smaller. Therefore. the value of this critical suction may be varied at the will of the designer. While the suction at. tlie delivery orifice is lower than the critical suction. the flow follows the law of an ordinary simple suction jet, and is equivalent to the flow through a virtual jet, the opening of which is a function of thesize of the fuel hole leading into the atmospheric well and of th size of the discharge hole from the well. \Vhen the suction is higher than this critical suction, the law of flow changes and is intermediate a pure gravity flow and a pure suction flow. If the well is widely opened to the air. this flow is practically due to the gravity alone, but if the well opening to the air is restricted, there will be some degree of suction in the well and the flow of fuel therein will depart from a true gravity flow. This deviation from the constant flow will depend on the respective sizes of the discharge holes frl'pm the well and the opening to the atmosp ere.

Referring more particularly to Figure 1,

' there is illustrated diagrammatically a carburetor comprising a constant level chamber 2 having afuel inlet 3 and a fuel outlet 4 adapted to supply. fuel. through a calibrated orifice, 5 to an atmospheric well or wells 6. From the atmospheric well. or wells, I may provide at different. levels a series of fuel feeding jets 7, 8, and 9 adapted to supply fuel to the carbureting passage 10 of a carhuretor. These jets may terminate in the venturi at any desired point with respect to the point of maximum constriction of the venturi 11, but preferably at a point where they are subjected to the -pressure.prevailing in the region of maximum depression. The carhureting passage 10 may he provided with the usual air inlet 12 and with a controlling throttle 13 of any desired construction. These jets usually extend a short distance above the level of the, fuel in the constant level chamber.

With a carburetor construction of this character, it will be apparent that when the carburetor is under no suction, which conditlon prevails when the motor is at rest, the level of the fuel in theconstant level cham- .ever, constitute but a small proportion of the total amount of fuel being fed, as it represents but-one of three of the fuel streams,

and the. feeding of such an emulsion will onlycontinue for a very brief period or until such timeas the level of the fuel in the atmospheric well supplying the jet 7 passes below the orifice 14. After this time, the jet 7 will feed air only, to the carhureting' passage. The suctionat which the level of the fuel in the atmospheric, well reaches the orifice 14 may be termed the first critical suction. I have found'thatuntil this suction is reached the flow from the el sysflow from an ordinary suction-controlled jet connected to the constant level chamber by. a

passage sufficiently large to offer practically no restriction totheflow. The area of this virtual jet depends upon the'ratio of the calibrated orifice 5 to the sumof the discharge orifices 14, 15 and 16.; The size of the atmospheric well feeding the jet has practically no influence upon this flow when a stable condition is reached, i. e., a condition at which the'level'of the fuel within the Well remains substantially constant. The size of the well until such stable condition or critical suction is reached is, however, of importance as it determines the amount of additional fuel which will be fed to the car-- buretor whenpassing from a lower to a higher suction. This is true for'the reason that the flowfrom the atmospheric well or wells, represented by the difference between the higher and the lower levels therein, is in addition to the normal flow.

If the transition from lower to higher suction is' slow and gradual, this reserve or additional flow will be spread out over a longer time than if the transition is a sud den one.

It will be apparent that in passing through this critical suction, there is a sudden change from one law governing the flow to a different law, as orifice 14 does not sup; ply fuel any longer, and only air will pass the ethrough. The flow of fuel will then be equivalent to the flow through a virtual single suction jet, the size of which is determined only by the sizes of. orifices 5, on one hand, and the sum of 15 and 16 on the other. This second virtual jet is smaller than "tent follows exactly, the same law as the V the first virtual jet and the tendency to increase the richness'of the mixture is therefore counteracted. By the present invention I speed, will not materially affect the level of the fuel ilithe atmospheric well beyond that referred to.. If, however, the .throttle is opened wider and the speed of the motor is increased, the suction will-increase to such an extent that the level of the fuel will begradually lowered beyond the level produced when operating at the first critical suction. If thiscondition is continued, a second critical suction will be reached, at which the discharge orifice 15 supplying the jet Swill be uncovered. Orifice 15 doesv not supply fuel any longer, and the flow of fuel wi 1' be equivalent to the fiow through a virtual single suction jet which is of smaller size than the second virtual jet which orifice 15 has eliminated. At this time, the operations which occurred at the first critical suetion will be repeated. Still further increase in engine speed may result in the production of a third critical suction at which the. dis. charge orifice 16 supplying the jet 9 will be uncovered. It is also obvlous that the size of the orifices may be so chosen that the thirdcritical suction may be very highand near the highest suction which the motor mayccreate.

It will be obvious that the number of jets and wells may be varied, and that both the area of the discharge orifices leadihg thereto and the location of these orifices may be changed.v Preferably, the construction will be such that with a carburetor of this type the third critical suction would be very high and in the upper limits of the'suction range.

A carburetor of this construction is effective for supplying a constant mixture of fuel and air, as it is equivalent broadly to a carburetor having a single suction jet with a metering orifice decreasing as thesuction increases. In this respect it differs materially from the ordinary single suction jet carburetor having a flow which is a function of the suction and which increases as the suction increases.

In Figure 2 I have illustrated diagrammatically a carburetor embodying the principles of construction shown in the Baverey patent hereinafter referred. to. In this construction the float chamber 2 delivers fuel both to an atmosphericwell 6 and to a main suction'jet 17. The-flow from the constant level chamber into the atmospheric well is preferably through a calibrated orifice5, tively, communicate with the atmospheric as before described, and the well is adapted to supply a compensating jet 18 through a discharge orifice 19. In order to eliminate the formation of a bad spot, there is also provided one or more jets 20 each adapted to e supplied through a discharge orifice 21 from the atmospheric well, With this construction, at the first critical suction the dis charge orifice 21 will be uncovered. At the ;second critical suction, if only one supplemental jet is provided, the discharge orifice 19 will be uncovered, and thereafter the carburetor will operateon the principle of Baverey Ratent No. 907,953 of Dcc.29,,1908.- It will be apparent that the o1'ifice-19'may be so proportioned as to delay this operation, whichis in accordance with the ordinary zenith principle, as desired." At the. first 1 critical suction, however, there willbe a brief period during which pure fuel w ll be'supplied in two streams while an emulsion supply is being supplied in a third stream from the jet 20. This condition is,- as pointed out, of extremely short duration, and immediately thereafter the jet 20 supplies only air.

With both forms of the invention; it will be apparent that' there are. provided ets each of which has but a single air inlet, whereby the flow through one of the ets .may bevaried without modifying the flow through the other jets. Until the first cr1 t1- cal. suction is reached, the threejets all g ve out pure fuel in proportion to. their discharge areas. After the first critical suction is reached, the first .jet --will no longer receive any fuel, but will discharge air only,

as the other jets under higher suction are of Sufficient capacity to take care of the fuel,

whole suction range will be increased, while increase in the area of the upper discharge orifice which is uncovered at the first crit ical suction will increase the richness at 'low suction and will result in a lower critical suction for this orifice.

In Figures 3, 7, 8 and 9, there is illustrated H the commercial embodiment of a carburetor constructed in accordance with the disclosure of .Figure 2. In this constructiom the jets 17, 18 and 20 are illustrated as being of sue:- cessively larger diameters arranged one w thin the other. The'nnain suction jet 17 receives its supply of fuel through the channel 22 having an area sufiiciently large to afford practically no restriction to the flow therethrough; while the jets 18 and '20, respecwell 6, having an opening 23 to the atmosphere, at successively higher levels. The well 6' is illustrated as having a priming device cooperating therewith comprising a quill 24 adapted to discharge into the carbureting passage ,10 through an orifice 25 located adjacent the throttle 13.

By reference more particularly to Figure 7, it will be apparent that the main suction jet 17 is provided with a threaded enlargement 26' adapted to be screwed into position in the vertically disposed interiorly threaded opening 27 in the body of the carburetor. After the jet l7 is in position, the compensating jet 18 having a threaded enlargement 28 is then threaded into position. After this, the jet 20, illustrated as being in the form of a cap jet, is also screwed into position. This construction provides a composite jet having a series of concentric annular passages each adapted to supply fuel as set forth.

In Figures-4 and'7, the inner jet is illustrated as terminatin below the outlet orifice ofthe other jets. T is construction is, however, not essential, and .in Figure 5 thejets are illustrated as terminating in substantial- -ly the same plane, while in Figure 6 they are illustrated as terminating in the reversed stepped relation. The jets may be modified to change the point of discharge in the venturi as desired. p

By the present invention, I am able to overcome the objectionable features of the bad spot as usually produced, and this constitutes an important advantage of the present invention.

I claim:

In a carburetor having a constant level chamber and a carbureting passage, a venturi in said passage, an atmospheric well having a restricted connection directly to said chamber, a fuel-feeding device adapted to deliver fuel throughout the entire range of operation of the carburetor, and a plurality of other fuel-feeding devices adapted to separately receive fuel from said well discharge the same within said venturi, substantially as described.

In testimony whereof I have hereunto set my hand.

VICTOR R: I-IEFTLER.

only and at diflerent levels and to separately 

